1. Field of the Invention
The present invention relates to a method of stabilizing the ground in road construction work. The method is applicable to the construction of new roads, or highways, and the reinforcement of existing roads or highways.
2. Description of the Related Art
It is necessary to stabilize weak subsoils when constructing new roads. Marshy ground and cohesive soils whose ultimate bearing resistance is too poor to support a new road construction are normally excavated down to a solid bottom and the resultant cavity refilled with suitable material, such as friction soil.
When it is necessary to excavate down to extreme depths in order to reach a solid bottom, for instance depths exceeding five meters, excavation and refilling is combined with pressing down of a heavy refill material, such as rock. When the weight of the heavy refill material becomes greater than the resistance of the underlying soil, the soil is pressed to one side. It is normally necessary to apply an overload to the ultimate road section, in order to force down the masses. It is normally necessary to leave the overload in place for a period of from 6 to 12 months before it can be removed.
Extremely fine soils are also excavated. The depth to which such soils are excavated will vary with climatic zones and also with respect to the flatness or evenness required of the finished road. Such soils can be excavated to a depth of approximately two meters.
Pronounced layers of clay soils can be piled (poled) or drained vertically.
Of the aforesaid methods, the excavation of unsuitable soil and refilling with suitable soil is the safest and often the most economical method.
However, the method causes the environment to be laden with excavated soil, etc., since these masses must be dumped in outlying tips and suitable masses taken from outlying deposits. The environment is therewith burdened by comprehensive transportation of excavated and suitable masses.
The bearing capacity of a road is often the major problem in the reconstruction of existing roads. This applies primarily when a gravel road is to be upgraded to a surfaced road. The upper construction of the road is normally replaced in such cases. Alternatively, the upper construction of the road is increased with a further construction, so as to achieve the desired bearing capacity. This procedure also requires masses to be taken from a suitable deposit and normally involves comprehensive transportation.
The present invention considerably reduces the need of excavating, refilling and transporting materials, both in the construction of new roads and when increasing the bearing capacity of an existing road.
The present invention thus relates to a method of stabilizing the ground in road construction work. A cement is mixed intensively with a microfill agent and optionally also a water reducing agent, so as to obtain a highly-reactive, dry cement mixture. The cement mixture is blended with at least one of the materials soil, clay or stone, and possibly water. The blend is laid on the ground to a thickness of at least 15-30 centimeters, causing the laid-out blend to contain sufficient cement blend to cure to obtain a compressive strength of at least 5 MPa 28 days after compaction. A roadbed is placed on top of the laid-out blend subsequent to said blend curing.